Giant Galaxies, Dwarfs, and Debris Survey. I. Dwarf Galaxies and Tidal Features around NGC 7331

Type Journal Article
Names Johannes Ludwig, Anna Pasquali, Eva K. Grebel, John S. Gallagher
Publication The Astronomical Journal
Volume 144
Pages 190
Journal Abbreviation The Astronomical Journal
Date December 1, 2012
DOI 10.1088/0004-6256/144/6/190;
ISSN 0004-6256
Library Catalog NASA ADS
Abstract The Giant GAlaxies, Dwarfs, and Debris Survey (GGADDS) concentrates on the nearby universe to study how galaxies have interacted in groups of different morphology, density, and richness. In these groups, we select the dominant spiral galaxy and search its surroundings for dwarf galaxies and tidal interactions. This paper presents the first results from deep wide-field imaging of NGC 7331, where we detect only four low-luminosity candidate dwarf companions and a stellar stream that may be evidence of a past tidal interaction. The dwarf galaxy candidates have surface brightnesses of μ r ≈ 23-25 mag arcsec-2 with (g - r)0 colors of 0.57-0.75 mag in the Sloan Digital Sky Survey filter system, consistent with their being dwarf spheroidal (dSph) galaxies. A faint stellar stream structure on the western edge of NGC 7331 has μ g ≈ 27 mag arcsec-2 and a relatively blue color of (g - r)0 = 0.15 mag. If it is tidal debris, then this stream could have formed from a rare type of interaction between NGC 7331 and a dwarf irregular or transition-type dwarf galaxy. We compare the structure and local environments of NGC 7331 to those of other nearby giant spirals in small galaxy groups. NGC 7331 has a much lower (~2%) stellar mass in the form of early-type satellites than found for M31 and lacks the presence of nearby companions like luminous dwarf elliptical galaxies or the Magellanic Clouds. However, our detection of a few dSph candidates suggests that it is not deficient in low-luminosity satellites.
Tags GALAXIES: EVOLUTION, GALAXIES: INTERACTIONS, GALAXIES: STRUCTURE, Galaxies: Dwarf, galaxies: formation, galaxies: groups: individual: NGC 7331
UW-Madison Astronomy Home